To establish and optimize a method for determining diacetyl content in popcorn, and determine the diacetyl content in popcorn sold in Weifang.Methods Popcorn pretreatment, diacetyl distillation extraction time, and absorption spectral scan condition were optimized to establish the method for the determination of diacetyl content in popcorn. Diacetyl content of 6 kinds of popcorns was determined with the method. Results The optimum extraction conditions of diacetyl content in popcorn were 40 meshes material granularity, 1∶5 materiel-liquid ratio, 30 min extraction time, 20 min reaction time, and 335 nm wavelength detection. The diacetyl content of 6 kinds of popcorns was 7.15,0.85,5.05,7.50,7.40 and 6.25 mg/kg respectively.Conclusion The method is simple and easy to operate, and it has good regression and reproducibility. The diacetyl content of 6 kinds of popcorns was within the prescribed scope of Flavour Extract Manufacturers′ Association (FEMA).